1. Field of the Invention
The invention relates generally to suction cups for holding objects, and more particularly, to a suction cup with an attachment for holding signs and other objects.
2. Description of Related Art
Suction cups with attachments for holding things are well known in the art. For example, it is well known to provide a suction cup having some type of clamp device connected to the neck of the suction cup for holding relatively thin flat objects, such as signs. Some examples of such suction cup sign holders are described in U.S. Pat. Nos. 1,992,900 to Plante; U.S. Pat. No. 840,618 to Golombek; U.S. Pat. No. 1,575,789 to Phelps; U.S. Pat. No. 253,392 to Jones et al.; U.S. Pat. No. 4,279,396 to Bendock; U.S. Pat. No. 1,847,403 to Loughman; U.S. Pat. No. 5,356,102 to Blumenaus and U.S. Pat. No. 2,276,992 to Manzler. The suction cup sign holders described in Plante, Golombek, Phelps, Jones, Bendock and Loughman each have a clamp member connected to the neck of the suction cup which has a pair of arms between which the sign is clamped. In each case, some means is provided for separating the arms to insert the object and then for biasing the arms closed to hold the object once it is inserted therebetween. In Blumenaus and Manzler, the clamp device has only one arm which clamps the object between the arm and the surface to which the suction cup is attached. Like the other devices though, some means is provided for moving the arm away from the other clamping surface to insert the sign and then biasing the arm back towards that surface to hold the object therebetween.
Other types of suction cup holders are disclosed in U.S. Pat. No. 1,839,694 to Nelson et al. and U.S. Pat. No. 2,467,251 to Bowman . In Nelson, there is no clamp member. Instead, the neck of the suction cup is provided with a slit partially through the neck portion. The resiliency of the material from which the neck portion is formed causes the slit to tend to remain closed. The neck can be bent to open the slit to insert a thin object therein and then released so that the slit closes to hold the object. An obvious limitation to such device is the relatively limited amount of gripping force which Obtained. In Bowman, the neck of the suction cup is formed into a bracket-like member having spaced apart arm portions between which an object, such as a pair of eye glasses may be inserted and supported. The arms are not biased toward each other but, instead, the space therebetween is sized to frictionally hold an object having a certain width, such as the bridge of a pair of glasses.
In all of the devices previously described suction cup sign holders utilizing a clamping device to hold signs, the sign is held either between two arms of the clamp or between an arm of the clamp and the surface to which the suction cup is attached. As such, the holding power of the clamp is a function of the clamping force and the coefficient of friction between the sign and either the clamp arms or the surface to which the suction cup is attached. In each of these suction cup clamp devices, the clamp arms are made from a relatively hard, smooth material. Also, the surface to which the suction cup is attached is normally hard and very smooth. The coefficient of friction between hard, and especially smooth, objects is typically much lower than the coefficient of friction of a relatively soft material, such as the type of vinyl from which suction cups are normally made. None of the described suction cup and clamp devices utilize the soft vinyl surface of the neck portion as one of the clamping surfaces between which the sign is held. Although the suction cup holders described in Nelson and Bowman do employ the soft material of the suction cup as part of the holding members, there is no clamp member to provide sufficient clamping force to securely hold relatively thick or heavy signs.
To increase the gripping power of the devices using clamps, the spring force biasing the clamp members toward each other, or toward the surface which the suction cup is attached, generally has to be increased. Increasing the biasing force can result in making it harder to open the clamp which also can increase the likelihood that the suction cup will inadvertently detach from the surface to which it is attached while attempting open the clamp to insert the sign.
Thus, there is a need for a suction cup sign holder which can grip the sign between a clamp member and the relatively soft neck of the suction cup to obtain increased gripping strength by virtue of greater friction instead of increasing the amount force biasing the clamping surfaces together.